Administering medication via injection requires the filling of an injection needle's vial from a supply of medicine. However, in emergency and/or field situations, time and/or sanitation is compromised if an injection needle needs to be filled prior to use. Pre-filled single-dose injectors typically have a removable cap slid over the injector's needle. Unfortunately, existing pre-filled single-dose injectors are not robust enough for the rough handling that can be associated with emergency and/or field environments. Furthermore, there are other emergency and/or field applications that require medicine to be dispensed via an atomizer or intravenous drip line in which case the pre-filled needle-tipped injector is no longer of value.